Manufacturers of alkyl-silica columns (e.g., C8, C18) for high- performance liquid chromatography (HPLC) are currently unable to guarantee that different production batches of nominally equivalent column packing will provide the same retention and separation of different samples. This in turn can lead to a number of related problems during the development and/or use of an HPLC method. Software (RP-COLUMN) that we propose to develop will (a) allow differences in column retention to be minimized by a predictable change in one or more separation conditions (e.g., temperature, pH, etc.), (b) correct for changes in the column during use, (c) facilitate method transfer between laboratories, (d) allow the more reliable duplication of HPLC procedures from the literature, (e) diagnose and correct problems due to error in the selection of experimental conditions (troubleshooting), (f) improve the resolution and robustness of a previously developed procedure, (g) allow the user to characterize any reversed-phase column in terms of its selectivity, (h) provide a data base for the selectivity characteristics of columns of different type and source and (i) select separation conditions such that quite different columns will perform adequately when used with a given procedure (HPLC method). These proposed nine applications of RP- COLUMN each represent a solution to a significant problem in the development or use of HPLC procedures. Applications (a-f) are based on the fact that retention as a function of simultaneous change in several variables (conditions) can be predicted on the basis of a small number of experiments. Applications (g) and (h) require an expanded insight into the retention process for reversed-phase HPLC, while application (i) addresses the problem of column variability in an entirely different fashion. PROPOSED COMMERCIAL APPLICATIONS: The proposed product RP-COLUMN will be regarded as an important addition to virtually every laboratory carrying out HPLC analysis. Manufacturers of HPLC equipment will probably want to incorporate the features of this software into their own data systems and system controllers. We expect initial sale-of $2-5 MM/year.